What version of Premiere Elements and on what computer operating system is it running?
Select all the photos (all at one time), right click anywhere in the selection, select Time Stretch, and, in the Time Stretch dialog,
change the duration field setting from whatever it is now to your wanted still duration....(if you had 5 second clips and wanted 1 second clips, then 00;00;05;00 changed to 00;00;01;00).
If you want to set for a still image duration BEFORE you import the photos so that the photos will all import with the duration that you want, set the Still Image Default Duration in preferences (Edit Menu/Preferences/General).
Any questions or need clarification, please do not hesitate to ask, but give details of version, computer operating system for detail specific suggestions.